A printing plate material for CTP capable of recording digital data employing a laser beam is required to be more highly light-sensitive for the purpose of carrying out recording in a short time. Further, recently, there has been a strong demand for processing (room light processing) under yellow light or white light, instead of processing in a dark room.
At present, a compact and high power laser emitting a blue-violet light with a short wavelength of from 390 to 430 nm has become available on the market, and a light sensitive planographic printing plate material suitable for this laser has been developed, which enables room light processing (see for example, Japanese Patent O.P.I. Publication Nos. 2000-98605, pages 2 and 3, sections 0005 to 0010, 2000-147763, page 3, sections 0006 to 0014, and 2002-202594, pages 2 and 3, sections 0004 and 0005.).
Since the yellow or yellow-orange light provides sufficient brightness, it is considered that there is no problem in these techniques with regard to workability under that kind of light. However, the yellow or yellow-orange light environment is psychologically undesired for operators worker, and therefore, an environment closer to white light has been desired.